Low Bitrate Asynchronous Replication of Block Devices and Virtual Machines

We present a system for asynchronous replication of virtual machines (running on top of QEMU-KVM and Lguest). The system uses a home-grown block device replication layer for data replication and includes VM replication components for Lguest and QEMU-KVM. We describe both of these components in this paper. Unlike previous works in the field, we focus on low bit rate systems. We target environments with low band-width that make frequent migration impossible. We put bandwidth preservation and operation continuity at the top of our priorities. To this end we are willing to sacrifice performance in order to preserve decent operation continuity even in low bit rate environments. We focus on SOHO environments as our target market. SOHO environments are often characterized by low requirements for actual performance and disk usage. However, SOHO environments are also limited in bandwidth capacity, especially upstream. All of these are taken into careful consideration throughout this paper.